Ink jet recording apparatus

ABSTRACT

Provided is an ink jet recording apparatus including: a base metal pigment ink composition; and a first nozzle that ejects the base metal pigment ink composition, in which the base metal pigment ink composition contains a flat base metal pigment of which a 50% average particle diameter D50 is in a range of 100 nm to 1 μm, and an organic compound of which a surface tension at 20° C. is 35 mN/m or greater, and an ejection interval T1 after the base metal pigment ink composition is ejected from the first nozzle and before the base metal pigment ink composition is ejected again from the first nozzle is within 100 μs.

BACKGROUND

1. Technical Field

The present invention relates to an ink jet recording apparatus.

2. Related Art

In the related art, as a method of forming a coated film having metallicluster on printed matter, foil stamp printing using print ink includinggold dust or silver dust manufactured from brass or aluminum fineparticles as a pigment or a metal foil, a heat transfer system using ametal foil, or the like has been used. However, according to the method,the forming of fine patterns or the application thereof to a curvedsurface portion is difficult. In addition, during the foil stampprinting, on-demand performance is low, the support for themulti-product production is difficult, and metal tone printing havinggradation cannot be performed.

Therefore, various application examples of the ink jet printing arepresented, and as an application example, metallic printing isperformed, development of the ink having metallic luster has progressed.The ink jet method is excellent in that the method can be applied to theforming of a fine pattern or the recording on a curved surface portion.As the metallic ink used in the ink jet method, ink for ink jetrecording that contains a metal pigment (scale-like pigment) such as analuminum is disclosed in JP-A-2013-227454 and JP-A-2013-199034.

The metal pigment disclosed in the patent document described above maypresent uneven behavior in the ink jet recording apparatus or in aportion near the nozzle of the ink jet head, caused by the specialshapes or particle diameters thereof. In this case, the flowability ofthe ink containing the metal pigment in the ink jet recording apparatusdecreases and thus the ejection of the ink becomes unstable.Particularly, as the interval of the ejection time of the ink ejectedfrom a specific nozzle decreases, the decrease in the ejection stabilityof the ink becomes considerable.

SUMMARY

An advantage of some aspects of the invention is to provide an ink jetrecording apparatus that can realize excellent ejection stability evenif the ejection interval of the ink is caused to be short.

The invention can be realized in the following forms or applicationexamples.

APPLICATION EXAMPLE 1

According to an aspect of the invention, there is provided an ink jetrecording apparatus including: a base metal pigment ink composition; anda first nozzle that ejects the base metal pigment ink composition, inwhich the base metal pigment ink composition contains a flat base metalpigment of which a 50% average particle diameter D50 is in a range of100 nm to 1 μm, and an organic compound of which a surface tension at20° C. is 35 mN/m or greater, and an ejection interval T1 after the basemetal pigment ink composition is ejected from the first nozzle andbefore the base metal pigment ink composition is ejected again from thefirst nozzle is within 100 μs.

According to the ink jet recording apparatus in Application Example 1,even if the ejection interval of the ink is short, within 100 μs,excellent ejection stability (waveform responsiveness) can be realized.

APPLICATION EXAMPLE 2

In the ink jet recording apparatus according to Application Example 1, adifference between a 90% average particle diameter D90 of the base metalpigment and a 10% average particle diameter D10 of the base metalpigment (D90−D10) may be in a range of 0.1 μm to 0.8 μm.

APPLICATION EXAMPLE 3

In the ink jet recording apparatus according to Application Example 1 or2, a 90% average particle diameter D90 of the base metal pigment may bein a range of 0.3 μm to 1.2 μm.

APPLICATION EXAMPLE 4

The ink jet recording apparatus according to any one of ApplicationExamples 1 to 3 may further include a color ink composition containing acolorant and a second nozzle that ejects the color ink composition, thecolorant may be a dye, or a pigment in which a 50% average particlediameter D50 is 400 nm or less, and when an ejection interval after thecolor ink composition is ejected from the second nozzle and before thecolor ink composition is ejected again from the second nozzle isreferred to as T2, a ratio between T1 and T2 (T1:T2) may be in a rangeof 0.7:1 to 1:0.7.

APPLICATION EXAMPLE 5

In the ink jet recording apparatus according to any one of ApplicationExamples 1 to 4, a diameter of the first nozzle may be 30 μm or less.

APPLICATION EXAMPLE 6

In the ink jet recording apparatus according to any one of ApplicationExamples 1 to 5, the ink jet recording apparatus may be a line-type inkjet recording apparatus that causes one of a recording head or arecording medium to be fixed and scans the other so as to record animage on the recording medium, and the first nozzle, and a second nozzlethat ejects a color ink composition containing a colorant which is adye, or a pigment having a 50% average particle diameter D50 of 400 nmor less may be installed on different recording heads, and arranged in adirection of the scanning.

APPLICATION EXAMPLE 7

In the ink jet recording apparatus according to any one of ApplicationExamples 1 to 5, the first nozzle and a second nozzle that ejects acolor ink composition containing a colorant which is a dye, or a pigmenthaving a 50% average particle diameter D50 of 400 nm or less may beinstalled on the same recording head, the recording head may include afirst nozzle array and a second nozzle array and performs scanning in amain scanning direction, the first nozzle array may contain the firstnozzle, and a plurality of nozzles that eject the base metal pigment inkcomposition may be arranged in a sub scanning direction intersecting themain scanning direction, the second nozzle array may contain the secondnozzle, and a plurality of nozzles that eject the color ink compositionmay be arranged in the sub scanning direction, and the first nozzlearray and the second nozzle array may be used in a divided manner forevery groups including a predetermined number of nozzles in the subscanning direction.

APPLICATION EXAMPLE 8

In the ink jet recording apparatus according to any one of ApplicationExamples 1 to 7, the organic compound may be at least one of aheterocyclic compound and an active energy ray polymerizable compound.

APPLICATION EXAMPLE 9

In the ink jet recording apparatus according to any one of ApplicationExamples 1 to 8, the content of the organic compound may be 5% by massor greater with respect to a total mass of the base metal pigment inkcomposition.

APPLICATION EXAMPLE 10

In the ink jet recording apparatus according to any one of ApplicationExamples 1 to 9, the base metal pigment may be a pigment subjected to asurface treatment with a fluorine-based compound, and the fluorine-basedcompound may contain fluorine, and at least one selected from the groupconsisting of phosphorus, sulfur, and nitrogen, as constituent elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a block diagram illustrating a configuration of an ink jetrecording apparatus according to an embodiment of the invention.

FIG. 2 is a diagram schematically illustrating a configuration of aserial printer which is an example of the ink jet recording apparatusaccording to the embodiment of the invention.

FIG. 3 is a diagram schematically illustrating a nozzle surface of arecording head of the serial printer.

FIGS. 4A and 4B are diagrams schematically illustrating a configurationof a line printer which is an example of the ink jet recording apparatusaccording to the embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the preferred embodiments of the invention are described.The embodiments described below provide examples of the invention. Theinvention is not limited to the embodiments below, and includes examplesof various modifications without departing from the gist of theinvention.

The ink jet recording apparatus according to an embodiment of theinvention includes a base metal pigment ink composition and a firstnozzle that ejects the base metal pigment ink composition, and the basemetal pigment ink composition contains a flat base metal pigment ofwhich a 50% average particle diameter D50 is in the range of 100 nm to 1μm and an organic compound of which the surface tension at 20° C. is 35mN/m or greater, and an ejection interval T1 after the base metalpigment ink composition is ejected from the first nozzle before the basemetal pigment ink composition is ejected again from the first nozzle iswithin 100 μs.

Hereinafter, the ink jet recording apparatus according to the embodimentis described in a sequence of the ink composition and the apparatus.

1. INK COMPOSTION

The ink jet recording apparatus according to the embodiment has a basemetal pigment ink composition as the ink composition thereof. The inkjet recording apparatus preferably further includes a color inkcomposition.

1.1. Base Metal Pigment Ink Composition 1.1.1. Pigment Dispersion Liquid

The base metal pigment ink composition according to the embodiment canbe obtained by using a pigment dispersion liquid as described below. Thepigment dispersion liquid according to the embodiment is a pigmentdispersion liquid for base metal pigment ink that contains a base metalpigment and an organic compound.

The base metal according to the invention may be a metal of which theionization tendency is greater than that in hydrogen, and conceptuallycan include, for example, single metal substances such as alkali metal,alkali earth metal, aluminum, iron, zinc, lead, copper, nickel, cobalt,and chrome, and an alloy thereof.

The base metal pigment included in the pigment dispersion liquidaccording to the embodiment is preferably pigment particles configuredwith a material containing a base metal (hereinafter, pigment particlesconfigured with material containing a base metal before surfacetreatment are referred to as “mother particles”) subjected to thesurface treatment with a fluorine-based compound.

Mother Particle

First, the pigment particle configured with a material containing basemetals (mother particles) is described. The mother particle may be amaterial of which at least an area including a portion near the surfaceis configured with a base metal, or the whole portion of the motherparticle may be configured with a base metal. In addition, the motherparticle may have a base portion configured with non-metal material anda coating film configured with a base metal with which the base portionis coated.

The base metal that configures the mother particle is not particularlylimited as long as the material is applicable to the aforementioneddefinition of the base metal. However, in view of glossiness securementand the cost, aluminum or an aluminum alloy is preferable. Here, thealuminum or the aluminum alloy has a problem in that if the aluminum orthe aluminum alloy is dispersed in an organic solvent, the oxidation ofthe aluminum is facilitated, and thus the glossiness decreases andaluminum is aggregated with each other. With respect to the problems, ifthe base metal pigment subjected to the surface treatment with thefluorine-based compound is used, the oxidation of the base metal pigmentcan be effectively suppressed. Therefore, the decrease in the glossinessof the solvent can be suppressed and the dispersibility is considerablyenhanced.

In addition, the mother particle may be manufactured by any method, but,for example, is preferably obtained by forming a film, formed with thebase metal, on one surface of the sheet-shaped base material by usingthe evaporation method, and then releasing the film formed with basemetal from the sheet-shaped base material and grinding the film. Insteadof the evaporation method, an ion plating or a sputtering method may beused. According to the method, since a flat mother particle can beobtained, glossiness inherent to the mother particle can be effectivelyexpressed.

As the sheet-shaped base material, for example, a plastic film such asone formed of polyethylene terephthalate can be used. In addition, inorder to improve releasability, the film formation surface of thesheet-shaped base material may be coated with a release agent such assilicone oil or the releasable resin layer may be formed on the filmformation surface. Examples of the resin used in the releasable resinlayer include a cellulose derivative such as polyvinyl alcohol,polyvinyl butyral, polyethylene glycol, polyacrylic acid,polyacrylamide, and cellulose acetate butyrate, or a modified nylonresin. The releasing and the grinding are performed by applyingultrasonic waves to the film in a non-aqueous medium or applyingexternal force by performing stirring with a homogenizer or the like.

In the method as described above, as the non-aqueous medium used whenthe releasing and the grinding are performed, alcohols such as methanol,ethanol, propanol, and butanol; a hydrocarbon-based compound such asn-heptane, n-octane, decane, dodecane, tetradecane, toluene, xylene,cymene, durene, indene, dipentene, tetrahydronaphthalene,decahydronaphthalene, and cyclohexylbenzene; an ether-based compoundsuch as ethylene glycol dimethyl ether, ethylene glycol diethyl ether,ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether,diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether,diethylene glycol monobutyl ether acetate, diethylene glycol n-butylether, tripropylene glycol dimethyl ether, triethylene glycol diethylether, propylene glycol monomethyl ether acetate, 1,2-dimethoxyethane,bis(2-methoxyethyl)ether, and p-dioxane; and a polar organic solventsuch as propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone,N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide,cyclohexanone, acetonitrile, and acryloyl morpholine can be suitablyused. If such a non-aqueous medium is used, unintentional oxidation ofthe mother particle or the like is prevented, and variations in sizes,shapes, and characteristics between the respective particles can bereduced.

Particularly, as the non-aqueous medium used when the releasing and thegrinding are performed, an organic compound of which the surface tensionat 20° C. is 35 mN/m or greater) (preferably in the range of 37 mN/m to45 mN/m) is preferably used. Accordingly, the more finely grinding canbe performed while the characteristics of the mother particles aremaintained. Therefore, the average particle diameter of the base metalpigment can be further decreased.

As the organic compound of which the surface tension at 20° C. is 35mN/m or greater, for example, a heterocyclic compound such as lactone, apyrrolidone derivative, cyclic amine, and cyclic ether are preferablyused. The specific examples of heterocyclic compound of which thesurface tension is 35 mN/m or greater include γ-butyrolactone,N-methyl-2-pyrrolidone, and acryloyl morpholine. If these organiccompounds are contained in the base metal pigment ink composition below,the glossiness of the recorded image may be further enhanced.

According to the invention, the measurement of the surface tension canbe measured by checking the surface tension when a platinum plate iswetted with the measuring object (organic compound, ink, or the like)under the environment of 20° C. by using an automatic surfacetensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.).

In addition, since the average particle diameter and the averagethickness of the mother particle are substantially the same as theaverage particle diameter and the average thickness of the base metalpigment below, the description thereof is omitted here.

Fluorine-Based Compound

Subsequently, the fluorine-based compound used in the surface treatmentof the mother particle is described. As described above, the base metalpigment included in the pigment dispersion liquid according to theembodiment is preferably the mother particle subjected to the surfacetreatment with the fluorine-based compound. As the fluorine-basedcompound, a compound containing fluorine, and at least one selected fromthe group consisting of phosphorus, sulfur, and nitrogen, as constituentelements, can be preferably used. Specific examples thereof includefluorine-based phosphonate, fluorine-based carboxylate, fluorine-basedsulfonate, and the salts thereof. If such a fluorine-based compound isused, the coating film can be formed by bonding a phosphonate group, acarboxy group, a sulfonate group, or the like to the surface of themother particle. Since the oxidation of the base metal pigment can beeffectively suppressed by using the base metal pigment coated with asingle layer or plural layers containing the fluorine-based compound inthe invention, the glossiness thereof in the organic solvent can besecured, and the dispersibility is considerably enhanced. Among these,fluorine-based phosphonate and the salts thereof are preferable sincethe bonding capability of the phosphonate group to the surface of themother particle is particularly excellent.

The fluorine-based phosphonate and the salts thereof preferably have astructure expressed by Formula (1) below.

In Formula (1) above, R¹'s each is one group selected from structuralformulas below, and M's each is a hydrogen atom, a hydrocarbon group, aunivalent metal ion, an ammonium ion, or —NR²R³R⁴. R², R³, and R⁴ areeach represent a hydrogen atom or a C₂H₄OH group, but a case in whichR², R³, and R⁴ all are hydrogen atoms is excluded. n is an integer inthe range of 1 to 3, m is an integer in the range of 1 to 12, and 1 isan integer in the range of 1 to 12.

In Formula (1) above, m is an integer in the range of 1 to 12, butpreferably an integer in the range of 1 to 8, and more preferably aninteger in the range of 1 to 5. In addition, 1 is an integer in therange of 1 to 12, but preferably an integer in the range of 1 to 10, andmore preferably an integer in the range of 1 to 6. If m and 1 are in thepreferable range described above, the effects described above are moreremarkably achieved.

As the fluorine-based phosphonate, a compound expressed by Formula (2)below is particularly preferable, since the balance between theabsorbability to the surface of the mother particle and the enhancementin weatherability is excellent.

In Formula (2) above, m is an integer in the range of 1 to 12, butpreferably an integer in the range of 1 to 8, and more preferably aninteger in the range of 1 to 5. In addition, 1 is an integer in therange of 1 to 12, but preferably an integer in the range of 1 to 10, andmore preferably an integer in the range of 1 to 6. If m and 1 are in thepreferable range described above, the effects described above are moreremarkably achieved.

The fluorine-based carboxylate and the salt thereof preferably have astructure expressed by Formula (3) below.

In Formula (3) above, R⁵ is one group selected from the structuralformulas below, and M is a hydrogen atom, a univalent metal ion, or anammonium ion. m is an integer in the range of 1 to 12, but preferably aninteger in the range of 1 to 8, and more preferably an integer in therange of 1 to 5. In addition, 1 is an integer in the range of 1 to 12,but preferably an integer in the range of 1 to 10, and more preferablyan integer in the range of 1 to 6.

The fluorine-based sulfonate and the salts thereof preferably have astructure expressed by Formula (4) below.

In Formula (4) above, R⁶ is one group selected from the structuralformulas below, M is a hydrogen atom, a univalent metal ion, or anammonium ion. m is an integer in the range of 5 to 17, and 1 is aninteger in the range of 1 to 12.

In addition, the fluorine-based compound preferably has a perfluoroalkylgroup (C_(n)F_(2n+1)) in at least a portion of the structure thereof,and the number of carbon atoms in the perfluoroalkyl group is morepreferably in the range of 1 to 6. If the fluorine-based compound hassuch a structure, the base metal pigment having excellent glossiness anddispersibility is easily obtained, and the weatherability when an imageis recorded tends to be more excellent.

In addition, the molecular weight of the fluorine-based compound ispreferably 1000 or less. If the fluorine-based compound adsorbed intothe surface of the mother particle is, for example, a fluorine-basedpolymer disclosed in JP-A-2003-213157, JP-A-2006-169393, andJP-A-2009-215411, the coating film becomes too thick to decrease theglossiness, and the interaction between the base metal pigments in whichthe coating films are formed becomes strong so that the dispersibilityis significantly decreased. Therefore, the film formed on the surface ofthe mother particle is preferably a monomolecular film formed of thefluorine-based compound having the molecular weight of 1000 or less.

Method of Manufacturing Pigment Dispersion Liquid

The pigment dispersion liquid according to the embodiment ismanufactured, for example, as follows.

First, dispersion liquid is prepared by dispersing the mother particledescribed above in the non-aqueous medium. After the dispersion liquidis diluted with a homogeneous or a heterogeneous non-aqueous medium ifnecessary, ultrasonic waves are applied until the average particlediameter (D50) of the mother particle becomes 1 μm or less, and thegrinding treatment is performed on the mother particle. The duration ofthe grinding treatment is not particularly limited, but is generally 3hours to 24 hours. In addition, specific examples of the non-aqueousmedium used in the dilution may include a non-aqueous medium which isthe same as the aforementioned non-aqueous medium when the releasing andgrinding is performed.

Subsequently, the coating film of the fluorine-based compound is formedon the surface of the mother particle by adding the fluorine-basedcompound to the dispersion liquid in which the mother particle subjectedto the grinding treatment is dispersed in the non-aqueous medium andapplying ultrasonic waves thereto. In this manner, the base metalpigment in which the surface of the mother particle is treated with thefluorine-based compound can be obtained. The addition amount of thefluorine-based compound is in the range of 1 part by mass to 50 parts bymass, preferably in the range of 2 parts by mass to 40 parts by mass,and more preferably in the range of 4.5 parts by mass to 30 parts bymass, with respect to 100 parts by mass of the mother particle. Inaddition, when the surface treatment is performed by applying ultrasonicwaves, heating may be performed. The heating temperature is preferably40° C. or higher. It is considered that the heating treatment forms acovalent bond between the surface of the mother particle and thefluorine-based compound, and thus the bonding strength is enhanced.

The surface treatment with the fluorine-based compound of the motherparticle may be performed directly on the surface of the motherparticle, or the treatment with the fluorine-based compound may beperformed on the mother particle treated with an acid or a base, inadvance. Accordingly, the chemical modification with the fluorine-basedcompound can be more securely performed on the surface of the motherparticle so that the effects of the invention as described above can bemore effectively achieved. In addition, even if the oxidation coatingfilm is formed on the surface of a particle which is to be the motherparticle before the surface treatment with the fluorine-based compoundis performed, the oxidation coating film can be removed so that thesurface treatment with the fluorine-based compound can be performed in astate in which the oxidation coating film is removed. Therefore, theglossiness of the manufactured base metal pigment can be caused to beexcellent. As the acid, for example, proton acid such as hydrochloricacid, sulfuric acid, phosphoric acid, nitric acid, boric acid, aceticacid, carbonic acid, formic acid, benzoic acid, chlorous acid,hypochlorous acid, sulfurous acid, hyposulfurous acid, nitrous acid,hyponitrous acid, phosphorous acid, and hypophosphoric acid can be used.Meanwhile, as a base, for example, sodium hydroxide, potassiumhydroxide, and calcium hydroxide can be used.

The product obtained up to this step can be used as the pigmentdispersion liquid, but it is preferable to further perform the solventsubstitution. A superfluous fluorine-based compound contained in thepigment dispersion liquid can be removed by performing solventsubstitution. If the superfluous fluorine-based compound exists in thepigment dispersion liquid, the dispersibility of the base metal pigmentmay be decreased. As a specific method of the solvent substitution, thesupernatant liquid is removed by centrifuging the above-obtaineddispersion liquid containing the fluorine-treated base metal pigment, anappropriate amount of the non-aqueous medium to be substituted is addedthereto, and the base metal pigment is dispersed in the substitutednon-aqueous medium by applying ultrasonic waves thereto. In this manner,the pigment dispersion liquid in which the base metal pigment isdispersed can be obtained. In addition, the pigment dispersion liquidobtained in this manner is preferably further heated. It is assumed thatthe fluorine-based compound ion-bonded to the surface of the motherparticle is dehydrated by heating to form a covalent bond, and themother particle and the fluorine-based compound are more strongly bondedso that the effect according to the invention as described above is moreeffectively achieved. The heating temperature is preferably 50° C. orhigher, and more preferably 60° C. or higher. The heat treatmentduration is preferably in the range of 1 day to 10 days.

In addition, the non-aqueous medium used in the substitution ispreferably the aforementioned organic compound (preferably, heterocycliccompound) of which the surface tension at 20° C. is 35 mN/m or greater.

In addition, surfactants may be further added to the non-aqueous mediumused in the substitution. The surfactant that can be added to thenon-aqueous medium is preferably a fluorine-based surfactant and/or asilicone-based surfactant. The content ratio of the surfactant in thenon-aqueous medium is preferably 3% by mass or less, more preferably inthe range of 0.01% by mass to 2% by mass, and particularly preferably0.1% by mass to 1% by mass. If the content ratio of the surfactant is inthe range described above, the dispersibility of the base metal pigmenttends to be further enhanced. In addition, a function as the slippingagent is expressed when the image is recorded, and thus the effect inwhich the abrasion resistance of the image is enhanced may be obtained.

Examples of the fluorine-based surfactant include Megaface F-430,Megaface F-444, Megaface F-472SF, Megaface F-475, Megaface F-477,Megaface F-552, Megaface F-553, Megaface F-554, Megaface F-555, MegafaceF-556, Megaface F-558, Megaface R-94, Megaface RS-75, and MegafaceRS-72-K (above are all product names of products manufactured by DICCorporation); EFTOP EF-351, EFTOP EF-352, EFTOP EF-601, EFTOP EF-801,and EFTOP EF-802 (above are all product names of products manufacturedby Mitsubishi Materials Corporation); Ftergent 222F, Ftergent 251, andFTX-218 (above are all product names of products manufactured by NeosCompany Limited); and Surflon SC-101 and Surflon KH-40 (above are allproduct names of products manufactured by AGC Semi Chemical Co., Ltd.).

Examples of the silicone-based surfactant include BYK-300, BYK-306,BYK-310, BYK-320, BYK-330, BYK-344, BYK-346, BYK-UV3500, and BYK-UV3570(above are all product names of products manufactured by BYK Japan KK);and KP-341, KP-358, KP-368, KF-96-50CS, and KF-50-100CS (above are allproduct names of products manufactured by Shin-Etsu Chemical Co., Ltd.).

The content ratio of the base metal pigment in the pigment dispersionliquid according to the embodiment is not particularly limited, but ispreferably in the range of 1% by mass to 10% by mass. If the contentratio of the base metal pigment in the pigment dispersion liquid is inthe range described above, the dispersibility of the base metal pigmentin the pigment dispersion liquid is easily enhanced, and the base metalpigment can be preserved for a long time. Physical properties of basemetal pigment

The shape of the base metal pigment contained in the pigment dispersionliquid according to the embodiment is a flat shape. If the shape of thebase metal pigment is a flat shape, the light reflectivity becomessatisfactory so that the image having excellent glossiness can berecorded.

According to the invention, the flat shape may be a shape in which anarea when observed from a predetermined angle (viewed from plane vision)may be larger than an area when being observed from a directionorthogonal to the viewing direction. Particularly, the ratio (S₁/S₀) ofan area S₁ [μm²] when being observed in the direction in which theprojected area becomes maximized (viewed from plane vision) and an areaS₀ [μm²] when being observed in a direction in which an area when beingobserved becomes maximized, among the directions orthogonal to theviewing direction is preferably 2 or greater, more preferably 5 orgreater, and particularly preferably 8 or greater. As the method ofdetermining the value, for example, 10 arbitrary particles may beobserved and an average value of values obtained by calculating theareas of the particles may be employed.

With respect to the base metal pigment contained in the pigmentdispersion liquid (base metal pigment ink composition) according to theembodiment, the 50% average particle diameter D50 has to be in the rangeof 100 nm to 1 μm, is preferably in the range of 100 nm to 850 nm, ismore preferably in the range of 100 nm or greater and less than 800 nm,is further more preferably in the range of 100 nm to 700 nm, is stillfurther more preferably in the range of 100 nm to 600 nm, and isparticularly preferably in the range of 100 nm to 550 nm. Since the D50of the base metal pigment is in the range described above, the imagehaving excellent glossiness can be recorded. In addition, if the D50 isin the range described above, the flowability of the base metal pigmentin the ink jet recording apparatus becomes satisfactory. Therefore, evenif the time interval at which the ink is ejected from a specific nozzleis short (within 100 μs), the ejection stability of the ink (waveformresponsiveness) becomes excellent. Meanwhile, if the D50 exceeds 1 μm,the flowability of the base metal pigment decreases, and as a result,when the time interval in which the ink is ejected from the specificnozzle is short, the ejection stability of the ink decreases.

With respect to the base metal pigment contained in the pigmentdispersion liquid (base metal pigment ink composition) according to theembodiment, a difference (D90−D10) between a 90% average particlediameter D90 and a 10% average particle diameter D10 is preferably inthe range of 0.1 μm to 0.8 and more preferably in the range of 0.2 to0.7 Here, a value of the difference (D90−D10) is an index indicatingwhether the monodispersity of the base metal pigment is satisfactory,and the monodispersity is evaluated to be more satisfactory when thevalue is smaller. If the value of the difference (D90−D10) is in therange described above, the arrangement of the base metal pigment on therecording medium becomes satisfactory, and the glossiness of therecorded image becomes excellent. In addition, since the flowability ofthe base metal pigment in the ink jet recording apparatus becomessatisfactory, even if the ejection interval is short, the ejectionstability (waveform responsiveness) of the ink becomes satisfactory.

With respect to the base metal pigment contained in the pigmentdispersion liquid (base metal pigment ink composition) according to theembodiment, the 90% average particle diameter D90 is preferably in therange of 0.3 μm to 1.2 μm, and more preferably in the range of 0.4 μm to1.0 μm. Accordingly, the glossiness of the recorded image, and theejection stability (waveform responsiveness) when the ejection intervalis short become satisfactory.

With respect to the base metal pigment contained in the pigmentdispersion liquid (base metal pigment ink composition) according to theembodiment, the 10% average particle diameter D10 is preferably in therange of 0.05 μm to 0.4 μm, and more preferably in the range of 0.1 μmto 0.3 μm. Accordingly, the glossiness of the recorded image, and theejection stability (waveform responsiveness) of the ink when theejection interval is short become satisfactory.

The light intensity distribution pattern of the diffracted scatter lightis detected by using a laser diffraction particle size distributionmeasuring apparatus, and the light intensity distribution patternthereof is calculated based on the light scattering theory to obtainvolume-based particle size distribution. The average particle diameteraccording to the invention refers to a volume average particle diametercalculated from the particle size distribution. Examples of the laserdiffraction particle size distribution measuring apparatus includeNanotrac UPA and Microtrac UPA (both are manufactured by Nikkiso Co.,Ltd.).

Specifically, “D50”, “D10”, and “D90” respectively refer to avolume-based cumulative 50% volume average particle diameter (D50), avolume-based cumulative 10% volume average particle diameter (D10), anda volume-based cumulative 90% volume average particle diameter (D90)obtained using a dynamic light scattering method, and are values thatcan be obtained in the following manner. Particles in the dispersionmedium are irradiated with light, and generated diffracted scatter lightis measured by a detector disposed on the front, lateral, and rear sidesof the dispersion medium. The particles which are originally amorphousparticles are assumed to be spherical, the total volume of a group ofparticles which are converted into spheres having the same volume asthat of the corresponding particles is set to be 100%, and a cumulativecurve is obtained by using the measured values. At this time, a point atwhich the cumulative value becomes 50% is the 50% average particlediameter (D50), a point at which the cumulative value becomes 10% is the10% average particle diameter (D10), and a point at which the cumulativevalue becomes 90% is the 90% average particle diameter (D90).

In addition, with respect to the base metal pigment contained in thepigment dispersion liquid (base metal pigment ink composition) accordingto the embodiment, the average thickness is preferably in the range of 1nm to 100 nm, and more preferably in the range of 5 nm to 50 nm. If theaverage particle diameter D50 and the average thickness of the basemetal pigment are in the range described above, when the base metalpigment is applied to an ink composition, an image having excellentsmoothness of a coated film and excellent glossiness can be recorded. Inaddition, the pigment dispersion liquid can be productivelymanufactured, and unintentional deformation of the base metal pigment atthe time of manufacturing the base metal pigment ink composition can besuppressed.

In addition, the average thickness can be obtained by photographing alateral image of the base metal pigment using a transmission electronmicroscope (TEM) or a scanning electron microscope (SEM), and obtainingand averaging the thicknesses of 10 base metal pigments. As thetransmission electron microscope (TEM), “JEM-2000EX” manufactured byJEOL Ltd. or the like is used, and as the scanning electron microscope,“S-4700” manufactured by Hitachi High-Technologies Corporation or thelike is used.

1.1.2. Base Metal Pigment Ink Composition

The base metal pigment ink composition according to the embodiment isprepared by using the pigment dispersion liquid described above, andincludes the base metal pigment and an organic compound of which thesurface tension at 20° C. is 35 mN/m or greater (hereinafter, alsoreferred to as “organic compound having specific surface tension”).

The base metal pigment ink composition according to the embodiment maybe an aqueous ink composition containing 50% by mass or more of water,or may be a solvent ink composition containing 50% by mass or more of anorganic solvent. In addition, the base metal pigment ink compositionaccording to the embodiment may be an active energy ray curing inkcomposition that is cured by the irradiation of an active energy ray.Examples of the active energy rays include infrared rays, ultravioletrays, X rays, electron rays, and the like, and the ultraviolet ray orthe electron ray are preferably used.

Base Metal Pigment

The content of the base metal pigment according to the embodiment ispreferably 0.1% by mass to 5.0% by mass, more preferably in the range of0.25% by mass to 3.0% by mass, and particularly preferably in the rangeof 0.5% by mass to 2.5% by mass, with respect to the total mass (100% bymass) of the base metal pigment ink composition.

Organic Compound Having Specific Surface Tension

The organic compound contained in the base metal pigment ink compositionand having the specific surface tension may be a product derived fromthe non-aqueous solvent contained in the pigment dispersion liquiddescribed above or a product newly added in the preparation of the basemetal pigment ink composition.

The base metal pigment ink composition according to the embodimentcontains the organic compound having the specific surface tension.Accordingly, since the leafing phenomenon of the base metal pigmenteasily occurs, the arrangement of the base metal pigment has beensatisfactory even before the base metal pigment is dried, and thus theglossiness of the recorded image is enhanced. With respect to theorganic compound having the specific surface tension, the surfacetension at 20° C. is 35 mN/m or greater, and preferably in the range of37 mN/m to 45 mN/m.

An example of the organic compound having the specific surface tensionincludes the heterocyclic compound described above. In addition, if thebase metal pigment ink composition according to the embodiment is theactive energy ray curing ink composition, an active energy raypolymerizable compound is included as the organic compound having thespecific surface tension. The heterocyclic compounds and the activeenergy ray polymerizable compounds may be used singly, or may be used incombination.

The active energy ray polymerizable compound has a characteristic ofbeing polymerized by the irradiation of the active energy ray singly ordue to the action of the well-known photoinitiator (for example, acylphosphine oxide compound) to cure the ink. As the active energy raypolymerizable compound, a monofunctional monomer containing a heteroatomin an alicyclic structure such astris(2-(meth)acryloyloxyethyl)isocyanurate, γ-butyrolactone(meth)acrylate, N-vinylcaprolactam, N-vinylpyrrolidone,pentamethylpiperidyl(meth)acrylate, tetramethylpiperidyl(meth)acrylate,mevalonic acid lactone(meth)acrylate, (meth)acryloylmorpholine, andtetrahydrofurfuryl(meth)acrylate can be preferably used. In addition, aproduct containing the other active energy ray polymerizable compoundmay be used. Among such active energy ray polymerizable compounds, inview of the enhancement of the glossiness of the recorded image,products of which the surface tension at 20° C. is 35 mN/m or greaterare preferably used. In the specification, (meth)acrylate means bothacrylate and methacrylate, and (meth)acryloyl means both acryloyl andmethacryloyl.

The content of the organic compound having the specific surface tensionis preferably 5% by mass or greater, and more preferably in the range of5% by mass to 40% by mass with respect to the total mass of the basemetal pigment ink composition. If the content is 5% by mass or greater,the glossiness of the recorded image is further enhanced. Meanwhile, ifthe content is 40% by mass or less, the meniscus can be stablymaintained, and stable and continuous ejection properties can besecured.

Organic Compound Not Having Specific Surface Tension

The base metal pigment ink composition according to the embodiment maycontain an organic compound in which the surface tension is less than 35mN/m (in the specification, referred to as “organic compound not havingspecific surface tension”). As the organic compound not having thespecific surface tension, an organic solvent which is a liquid mediumcan be used. As a specific example, the non-aqueous medium (except forthose in which the surface tension is 35 mN/m or greater) is included.Among these, the organic compound preferably contains one or more kindsof alkylene glycol ether which is liquid at normal temperature andpressure.

Examples of alkylene glycol ether include methyl, ethyl, n-propyl,i-propyl, n-butyl, i-butyl, hexyl, and aliphatics of 2-ethylhexyl, aswell as ethylene glycol-based ethers and propylene glycol-based etherswhich have each of allyl and phenyl groups having a double bond as abase group thereof. Since these examples are colorless, give out alittle odor, and have an ether group and a hydroxyl group in theirmolecules, these examples have properties of both alcohols and ethers,and are liquid at normal temperature. In addition, the examples may havemonoethers of which only an hydroxyl group on one side is substituted,or diethers of which hydroxyl groups on both sides are substituted, andplural kinds thereof may be used in combination.

Examples of the alkylene glycol monoether include ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, ethylene glycolmonoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycolmonohexyl ether, ethylene glycol monophenyl ether, diethylene glycolmonomethyl ether, diethylene glycol monoethyl ether, diethylene glycolmonobutyl ether, triethylene glycol monomethyl ether, triethylene glycolmonoethyl ether, triethylene glycol monobutyl ether, tetraethyleneglycol monomethyl ether, tetraethylene glycol monoethyl ether,tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether,propylene glycol monoethyl ether, dipropylene glycol monomethyl ether,and dipropylene glycol monoethyl ether.

Examples of the alkylene glycol diether include ethylene glycol dimethylether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether,diethylene glycol dimethyl ether, diethylene glycol diethyl ether,diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether,triethylene glycol dimethyl ether, triethylene glycol diethyl ether,triethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether,tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether,propylene glycol dimethyl ether, propylene glycol diethyl ether,dipropylene glycol dimethyl ether, and dipropylene glycol diethyl ether.

If the organic compound having the specific surface tension and alkyleneglycol ether, of which the surface tension is lower than 35 mN/m areused in combination, the glossiness and the ejection stability thereofcan become compatible.

If the base metal pigment ink composition according to the embodiment isa non-aqueous ink composition, the content of the alkylene glycol ether,of which the surface tension is less than 35 mN/m, is preferably in therange of 40% by mass to 95% by mass with respect to the total mass ofthe base metal pigment ink composition.

Resin

The base metal pigment ink composition according to the embodiment maycontain a resin. Examples of the resin include an acryl resin, astyrene-acryl resin, a rosin-modified resin, a terpene-based resin, apolyester resin, a polyamide resin, an epoxy resin, a vinyl chlorideresin, a vinyl chloride-vinyl acetate copolymer, a cellulose-based resin(for example, cellulose acetate butyrate, and hydroxypropyl cellulose),polyvinyl butyral, polyacryl polyol, polyvinyl alcohol, andpolyurethane.

In addition, the non-aqueous emulsion-type polymer fine particles (NonAqueous Dispersion: NAD) can be also used as the resin. These aredispersion liquids in which fine particles such as the polyurethaneresin, the acryl resin, and the acryl polyol resin are stably dispersedin the organic solvent. Specific examples of commercially-availableproducts include Sanprene IB-501 and Sanprene IB-F370 manufactured bySanyo Chemical Industries, Ltd. as the polyurethane resin, and includeN-2043-60MEX and N-2043-AF-1 manufactured by Harima Chemicals Group,Inc. as the acryl polyol resin.

The resins may be used singly or two or more types thereof may be usedin combination.

The content (solid content) when the resin is contained is preferably inthe range of 0.05% by mass to 10% by mass, more preferably in the rangeof 0.1% by mass to 5% by mass, and particularly preferably in the rangeof 0.15% by mass to 2% by mass, with respect to the total mass of thebase metal pigment ink composition. If the content of the resin is inthe range described above, the fixability of the base metal pigment tothe recording medium is further enhanced.

Surfactant

At least one surfactant selected from the group consisting of afluorine-based surfactant and a silicone-based surfactant may be furtheradded to the base metal pigment ink composition according to theembodiment. The content of the surfactant is preferably 3% by mass orless, more preferably in the range of 0.01% by mass to 2% by mass, stillmore preferably in the range of 0.1% by mass to 1.5% by mass, andparticularly preferably in the range of 0.1% by mass to 1.0% by mass,with respect to the total mass of the base metal pigment inkcomposition. If the content of the surfactant is in the range describedabove, the wettability of the base metal pigment ink composition to therecording medium is enhanced, and the fixability of the base metalpigment to the recording medium is further enhanced. In addition, thefunction as the slipping agent is expressed in the recorded image sothat an effect in which the abrasion resistance of the image is enhancedcan be obtained.

As the fluorine-based surfactant and the silicone-based surfactant, theproducts described above that can be added when the pigment dispersionliquid is prepared can be used. The surfactants may be used singly, ortwo or more types thereof may be used in combination.

Other Components

The base metal pigment ink composition according to the embodiment maycontain components normally contained in the aqueous ink composition,the solvent ink composition, and the active energy ray curing inkcomposition, in addition to the components described above.

Method of Manufacturing Base Metal Pigment Ink Composition

A solvent-based ink composition according to the embodiment may beprepared in a well-known common method. For example, the solvent-basedink composition can be obtained by mixing and dissolving an organiccompound, a resin, and an additive to obtain an ink solvent, adding thepigment dispersion liquid containing the base metal pigment describedabove to the ink solvent, and further performing mixing and stirring atnormal temperature and pressure.

Physical Property of Base Metal Pigment Ink Composition

The viscosity of the base metal pigment ink composition according to theembodiment at 20° C. is preferably in the range of 2 mPa·s to 10 mPa·s,and more preferably in the range of 3 mPa·s to 5 mPa·s. If the viscosityof the base metal pigment ink composition at 20° C. is in the rangedescribed above, an appropriate amount of the base metal pigment inkcomposition is ejected from the nozzle so that the flight curvature orthe scattering of the ink can be further reduced. Therefore, the basemetal pigment ink composition can be properly used in the ink jetrecording apparatus.

In the invention, the measurement of the viscosity can be performed byusing a viscoelastic testing device MCR-300 (manufactured by Pysica),and by increasing shear rate to the range of 10 to 1,000 in theenvironment of 20° C., and reading the viscosity at the shear rate of200.

In addition, the surface tension of the base metal pigment inkcomposition according to the embodiment at 20° C. is preferably in therange of 20 mN/m to 50 mN/m. If the surface tension is 20 mN/m orgreater, the wetting-spreading or the bleeding of the base metal pigmentink composition to the surface of the recording head can be suppressed,and the ejection of the ink droplet can be satisfactorily performed. Ifthe surface tension is 50 mN/m or less, the ink can be easilywetting-spread to the surface of the recording medium so that printingbecomes satisfactory.

1.2. Color Ink Composition

The ink jet recording apparatus according to the embodiment preferablyhas a color ink composition further containing a colorant. In the samemanner as the base metal pigment ink composition, the color inkcomposition may be an aqueous ink composition, may be a solvent inkcomposition, or may be an active energy ray curing ink composition.

Colorant

The colorant is a dye, or a pigment of which the 50% average particlediameter D50 is 400 nm or less.

As the dye, for example, various dyes used in a normal ink jet recordingsuch as a direct dye, an acid dye, an edible dye, a basic dye, areactive dye, a disperse dye, a vat dye, a soluble vat dye, and areactive disperse dye can be used.

D50 of the pigment has to be 400 nm or less, but the pigment of whichD50 is in the range of 50 nm to 400 nm is preferably used. If thepigment having D50 of 400 nm or less is used, the ejection stability ofthe color ink composition is enhanced.

As the pigment, a well-known pigment such as an inorganic pigment or anorganic pigment can be used. The inorganic pigment is not limited to thebelow, and may be, for example, titanium oxide, iron oxide, calciumcarbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmiumred, chrome yellow, carbon black, prussian blue, and metal powder.

The organic pigment is not limited to the below, and may be, forexample, an azo pigment, a polycyclic pigment, a nitro pigment, anitroso pigment, and aniline black. Among these, at least one of the azopigment and the polycyclic pigment are preferable. Among these, the azopigment is not limited to the below, and may be, for example, an azolake, an insoluble azo pigment, a condensed azo pigment, and a chelateazo pigment. The polycyclic pigment is not limited to the below, but maybe, for example, a phthalocyanine pigment, a perylene pigment, perynonepigment, an anthraquinone pigment, a quinacridone pigment, a dioxazinepigment, an indigo pigment, a thioindigo pigment, an isoindolinonepigment, a quinophthalone pigment, an azomethine-based pigment, andrhodamine B lake pigment. The pigments may be used singly, or two ormore types thereof may be used in combination.

The content of the colorant can be appropriately set as desired, and maybe, for example, in the range of 0.1% by mass to 10% by mass withrespect to the total mass (100% by mass) of the color ink composition.

If a pigment is used as the colorant, in view of the enhancement of thedispersibility in the ink, the pigment may be a pigment subjected to thesurface treatment or may be a pigment using a dispersant. The pigmentsubject to the surface treatment refers to a pigment that can bedispersed in an aqueous solvent by directly or indirectly combining ahydrophilic group (carboxyl group, sulfonate group, phosphonate group,and the like) to a pigment surface by a physical treatment or a chemicaltreatment (hereinafter, also referred to as “self-dispersion pigment”).In addition, the pigment using the dispersant refers to a product inwhich the pigment is dispersed by a surfactant or a resin (hereinafter,referred to as “polymer dispersion pigment”), and well-known materialscan be used as both surfactant and resin. In addition, a pigment coveredwith the resin may be included in the “polymer dispersion pigment”. Thepigment covered with the resin can be obtained by an acid depositionmethod, a phase inversion emulsification method, and a mini-emulsionpolymerization method.

Other Components

The color ink composition according to the embodiment contains generallyused well-known components such as water, a resin, a surfactant, anorganic solvent, an active energy ray polymerizable compound, accordingto the use thereof such as an aqueous ink composition for ink jetrecording, a solvent ink composition, or an active energy ray curing inkcomposition.

Method of Manufacturing Color Ink Composition

The color ink composition according to the embodiment can be prepared bya well-known common method.

Physical Property of Color Ink Composition

The viscosity of the color ink composition according to the embodimentat 20° C. is preferably in the range of 2 mPa·s to 10 mPa·s, and morepreferably in the range of 3 mPa·s to 5 mPa·s. If the viscosity of thecolor ink composition at 20° C. is in the range described above, anappropriate amount of the color ink composition is ejected from thenozzle so that the flight curvature or the scattering of the ink can befurther reduced. Therefore, the color ink composition can be properlyused in the ink jet recording apparatus.

In addition, the surface tension of the color ink composition accordingto the embodiment at 20° C. is preferably in the range of 20 mN/m to 50mN/m. If the surface tension is 20 mN/m or greater, thewetting-spreading or the bleeding of the color ink composition to thesurface of the recording head can be suppressed, and the ejection of theink droplet can be satisfactorily performed. If the surface tension is50 mN/m or less, the ink can be easily wetting-spread to the surface ofthe recording medium so that printing becomes satisfactory.

2. INK JET RECORDING APPARATUS 2.1. Apparatus Configuration

The ink jet recording apparatus according to the embodiment includes thebase metal pigment and a first nozzle that ejects the base metalpigment. A more preferred embodiment of the ink jet recording apparatusaccording to the embodiment further includes the color ink compositionand a second nozzle that ejects the color ink composition.

Hereinafter, the apparatus configuration of the ink jet recordingapparatus according to the embodiment is described in detail withreference to the drawings. In addition, for better understanding of thestructure of the ink jet recording apparatus according to theembodiment, scales may be appropriately changed.

FIG. 1 is a block diagram illustrating a configuration of an ink jetrecording apparatus 1 (100) according to the embodiment. As illustratedin FIG. 1, the ink jet recording apparatus 1 (100) includes atransportation unit 10, a head unit 20, a detector group 60, and acontroller 70. The ink jet recording apparatus 1 (100) that receivesimage data from an input section 80 to which the image data is inputcontrols respective units by the controller 70. The controller 70controls respective units based on the image data received from theinput section 80, and records the image on a recording medium P. Thestate in the ink jet recording apparatus 1 (100) is monitored by thedetector group 60, and the detector group 60 outputs the detectionresult to the controller 70. The controller 70 controls the respectiveunits based on the detection result output from the detector group 60.The image data received by the ink jet recording apparatus 1 (100) fromthe input section 80 may be image data obtained by performing a processsuch as data conversion by the input section 80 on the image data inputfrom another apparatus (not illustrated) to the input section 80.

Specifically, the controller 70 is a control unit (control portion) forcontrolling the ink jet recording apparatus 1 (100), and includes aninterface portion 72, a CPU 74, a memory 76, and a unit control circuit78. The interface portion 72 transmits and receives the data between theinput section 80 and the ink jet recording apparatus 1 (100). The CPU 74is an arithmetic processing device for performs overall control of theink jet recording apparatus 1 (100). The memory 76 is to secure an areafor storing a program of the CPU 74 and a working area, and includes astorage element such as RAM and EEPROM. The CPU 74 controls therespective units via the unit control circuit 78, according to theprogram stored in the memory 76.

The input section 80 is a section for inputting image data to berecorded in the recording medium P, and includes, for example, a PC or atouch panel-type input device. The input section 80 may include afunction of performing data conversion on the image data input fromanother device. The input section 80 may be, for example, a PC in whicha printer driver that controls the ink jet recording apparatus 1 (100)is installed. The image data input into the PC performs data processingfor converting the data before the data processing (for example, imagedata in JPEG format) to data appropriate for performing recording on therecording medium P by the ink jet recording apparatus 1 (100) (forexample, image data in dot format).

2.1.1. Serial Printer

FIG. 2 is a perspective view schematically illustrating a structure ofthe ink jet recording apparatus 1, and an example in which the ink jetrecording apparatus is a serial printer (serial-type ink jet recordingapparatus). Hereinafter, the ink jet recording apparatus 1 illustratedin FIG. 2 is also called the serial printer 1. The serial printer refersto a printer including a mechanism in which a recording head is mountedon a carriage that performs scanning (moves) in a main scanningdirection, and an ink droplet is ejected to a recording medium by thescanning (movement) of a recording head accompanied by the scanning(movement) of the carriage.

As illustrated in FIG. 2, the serial printer 1 includes a transportationmechanism 11 that transports the recording medium P in a transportationdirection, a platen 12 that supports the recording medium P that isarranged on the lower side of a head 21, and transported, a carriage 23on which the head 21 is mounted and on which an ink cartridge 22 isdetachably mounted, and a carriage moving mechanism 24 that moves thecarriage 23 in a medium width direction of the recording medium P.Further, the serial printer 1 has the aforementioned controller 70 thatcontrols the overall operations of the printer 1. In addition, in FIG.2, the medium width direction is a main scanning direction in which thehead performs scanning, and the transportation direction is a directionintersecting the medium width direction (sub scanning direction).

Transportation rollers 11 and the platen 12 are examples of componentsof the transportation unit 10 in FIG. 1. The transportation roller 11transports the fed recording medium P in response to an instruction fromthe controller 70 in the transportation direction. In addition, theplaten 12 supports the transported recording medium P.

The recording head 21, the ink cartridge 22, the carriage 23, and thecarriage moving mechanism 24 are examples of the components of the headunit 20, and form an image by ejecting droplets of ink to the recordingmedium P in response to the instruction from the controller 70.

The carriage 23 is installed in a state of being supported by a guiderod 25 that is a supporting member built in the medium width direction.The carriage 23 moves in the medium width direction along the guide rod25 by the carriage moving mechanism 24, in response to the instructionfrom the controller 70. In addition, in the example of FIG. 2, themovement of the carriage 23 in the medium width direction isillustrated, but the invention is not limited thereto, and in additionto the movement of the medium width direction, a mechanism that moves inthe transportation direction may be provided.

For example, the ink cartridge 22 can be configured with 4 independentcartridges. Each of the 4 cartridges is filled independently with thebase metal pigment ink composition and the color ink compositionsdescribed above. In addition, in the example of FIG. 2, the number ofcartridges is 4, but the number is not limited thereto, and a desirednumber of cartridges can be mounted. The ink cartridge 22 is not limitedto a cartridge mounted on the carriage 23 as illustrated in FIG. 1, and,in substitution for this, for example, may be a cartridge that ismounted on a housing side of the serial printer 1 and supplies ink tothe head 21 via an ink supplying tube.

The recording head 21 changes its own position with respect to therecording medium P in association with the movement of the carriage 23,and ejects the droplets of the ink from a predetermined nozzle inresponse to the instruction from the controller 70.

FIG. 3 is a diagram schematically illustrating a nozzle surface of therecording head 21. The plurality of nozzle arrays 27 are arranged on thenozzle surface which is an ink ejection surface. The plural nozzlearrays 27 have plural nozzles 26 for ejecting the ink in each nozzlearray.

The plural nozzle arrays 27 can eject the ink having differentcompositions in each nozzle array. In the example of FIG. 3, 4 rows ofnozzle arrays corresponding to the ink compositions are provided, andthe respective nozzle arrays are arranged in the main scanningdirection. Specifically, 4 nozzle arrays such as a nozzle array 27A thatcan eject the base metal pigment ink composition described above and anozzle array 27B that can eject the color ink compositions describedabove are provided. In the example of FIG. 3, 4 rows of nozzle arraysare provided, but the invention is not limited thereto.

In the example of FIG. 3, the nozzle arrays 27A and 27B are respectivelyextended on the nozzle surface in the sub scanning directionintersecting the main scanning direction. However, the invention is notlimited thereto, and the nozzle arrays 27A and 27B may be disposed tohave an angle in a direction intersecting the main scanning direction onthe nozzle surface.

The plural nozzles 26 are arranged in a predetermined pattern to form anozzle array. According to the embodiment, the plural nozzles 26 arearranged on the nozzle surface in the sub scanning direction, but theinvention is not limited thereto, and the plural nozzles 26 may bearranged, for example, on the nozzle surface to form a zigzag shape in adirection orthogonal to the main scanning direction. In addition, thenumber of nozzles 26 that configures the nozzle array is notparticularly limited.

The plural nozzle arrays 27 can be used in a manner of being dividedinto plural areas including a predetermined number of nozzles 26 in thesub scanning direction. In the example of FIG. 2, the nozzle arrays 27Aand 27B are configured with a first group on a upstream side T1 in thesub scanning direction and a second group on a downstream side T2 of thefirst group in the sub scanning direction. In addition, the number ofnozzles 26 that configures one group is not particularly limited. Inaddition, the numbers of nozzles 26 that configures the groups may bethe same with each other or may be different from one another in eachnozzle array. In addition, the nozzle arrays may be used in a manner ofbeing divided into three groups. If the nozzle arrays are used in adivided manner, the high speed of the recording can be achieved. Inaddition, if the nozzle arrays are used in a divided manner, thebackfeeding of the recording medium may not be performed, or the numberof times of the backfeeding of the recording medium can be reduced.Accordingly, the deviation of the printing position that can easilyoccur due to the backfeeding of the recording medium can be reduced.

The printer that performs recording by dividing the nozzle arrays ejectsthe color ink composition and the base metal pigment ink composition inthe same scanning. Accordingly, in view of the increase in speed and thehigh definition of the image, the base metal pigment ink compositionalso strongly requires a performance of capable of being ejected at thesame speed as the ejection speed of the color ink composition.Accordingly, the ink composition that can be ejected at a high speed andof which the droplet lands at the same speed as the ejection speed ofthe color ink composition is preferably used in a printer in which thenozzle arrays are divided to perform recording.

The serial printer 1 may include a heating mechanism (not illustrated)that heats the recording medium. As long as the heating mechanism isinstalled at a position that can heat the recording medium P, theinstallation position thereof is not particularly limited. The heatingmechanism can be installed, for example, on the platen 12, and at aposition facing the recording head 21. In this manner, if the heatingmechanism is installed at a position facing the recording head 21, theattachment position of the droplet on the recording medium P can besurely heated so that the droplet attached to the recording medium P canbe effectively dried.

As the heating mechanism, for example, a print heater mechanism thatcauses the recording medium P to come into contact with a heat sourceand heat the recording medium P, a mechanism that performs irradiationwith an infrared ray, a microwave (electromagnetic wave having maximumwavelength of about 2,450 MHz), or the like, or a dryer mechanism thatblows a hot air may be used. In addition, the overall conditions of theheating (for example, whether to perform heating, the timing of theheating, the heating temperature, or the heating time) are controlled bythe controller 70.

If the active energy ray curing ink composition is used, the serialprinter 1 may include an irradiation section (not illustrated) so as tocure the droplet of the ink attached to the recording medium.

The irradiation section may be installed in any position as long as theirradiation section can irradiate the ultraviolet ray curing inkcomposition attached to the recording surface with the active energyray, and for example, the irradiation section may be provided on bothends of the recording head 21 in the main scanning direction.

The irradiation section includes a light source (not illustrated), and alight source control circuit (not illustrated) that controls whether toswitching on or off the light source. As the light source, anultraviolet ray emitting diode is preferably used. Accordingly, comparedwith the case where a mercury lamp, a metal halide lamp, the otherlamps, and the like are used as the light source, the increase of thelight source in size or in weight can be prevented. Therefore, theburden at the time of moving the carriage 23 can be reduced. Inaddition, when the ultraviolet ray emitting diode is used as the lightsource, the emission peak wavelength of the emitted ultraviolet ray maybe in the range of 350 nm to 420 nm.

2.1.2. Line Printer

FIGS. 4A and 4B are diagrams schematically illustrating a portion of thestructure when the ink jet recording apparatus 100 is viewed from theabove, and an example in which the ink jet recording apparatus is a lineprinter (line-type ink jet recording apparatus). Hereinafter, the inkjet recording apparatus 100 illustrated in FIGS. 4A and 4B is called theline printer 100. The line printer refers to a printer including amechanism in which one of the recording medium or the recording head isfixed and the other is scanned when the image is recorded, so that thedroplet of the ink is ejected by the plural nozzles installed throughoutthe entire body in the medium width direction.

The ink used in the line printer that performs recording at an ultrahigh speed is preferably ink that can be stably ejected at a high speed.In addition, if the ink can be ejected at the same ejection speed as thecolor ink composition, the landing positions of the base metal pigmentink composition and the color ink composition can be matched, so that abrilliantly colored image of the high definition can be obtained.Accordingly, the base metal pigment ink composition according to theinvention can be used in the line printer that scans the recordingmedium only in one direction.

FIG. 4A is a diagram schematically illustrating a portion near arecording area of the line printer 100 viewed from the above. Inaddition, FIG. 4B is a diagram schematically illustrating the recordingarea of the line printer 100 illustrated in FIG. 4A from one side. Asillustrated in FIGS. 4A and 4B, the line printer 100 includes a platen112 that transports the recording medium P in the transportationdirection and a recording head 121 that extends in a medium widthdirection. In addition, though not illustrated, the controller 70 thatcontrols the overall operations in the same manner as in the serialprinter 1 of FIG. 2 is provided at an arbitrary position in the lineprinter 100.

The platen 112 is an example of components of the transportation unit 10in FIG. 1. As long as the transportation unit 10 can transport therecording medium P, the transportation unit 10 is not limited to theplaten 112, a well-known mechanism can be used. The platen 112transports the fed recording medium P in the transportation direction inresponse to the instruction from the controller 70. In the example ofFIGS. 4A and 4B, the platen 112 is self-driven so that the recordingmedium P supported by the platen 112 moves in the transportationdirection.

The recording head 121 is an example of components of the head unit 20in FIG. 1. The recording head 121 is formed in the width direction ofthe recording medium P. The recording head 121 ejects a droplet of theink from a predetermined nozzle in response to the instruction from thecontroller 70. As illustrated in FIGS. 4A and 4B, the recording head 121includes plural recording heads such as a first recording head 121A thatejects the base metal pigment ink composition and a second recordinghead 121B that ejects the color ink composition. Specifically, fourrecording heads are included in the example of FIGS. 4A and 4B, but theinvention is not limited thereto, and two or more recording heads may beincluded.

In FIGS. 4A and 4B, the plural nozzles 126 including a first nozzle 126Aare provided in the first recording head 121A. The plural nozzles 126are arranged in the medium width direction. In addition, the pluralnozzles 126 including a second nozzle 126B are arranged in the secondrecording head 121B in the medium width direction. In this manner, thefirst nozzle 126A and the second nozzle 126B are provided on differentrecording heads, and arranged in the transportation direction (scanningdirection).

The line printer 100 may include a heating mechanism (not illustrated)that heats the recording medium. As long as the heating mechanism isprovided at a position that can heat the recording medium P, theinstallation position is not particularly limited. For example, theheating mechanism may be installed on the lower side of the platen 112and at a position facing the recording head 121. In this manner, if theheating mechanism is provided on a postion facing the head 121, theattachment position of the droplet on the recording medium P can besurely heated so that the droplet attached to the recording medium P canbe effectively dried. The mechanism that can be used in the heatingmechanism or the heating timing, and the control of the overallconditions of the heating are the same as those in the serial printer 1described above. Therefore, the description thereof is omitted.

When the line printer 100 uses the active energy ray curing inkcomposition, the irradiation section (not illustrated) for curing thedroplet of the ink attached to the recording medium may be included. Theirradiation section is provided at any position as long as theirradiation section can irradiate the active energy ray curing inkcomposition attached to the recording surface with the active energyray. For example, the irradiation section may be provided betweenrecording heads such as a portion between the first recording head 121Aand the second recording head 121B, or on the downstream side of therecording head on the downmost stream side. The irradiation section maybe installed so as to perform irradiation along the medium widthdirection.

2.1.3. Others

In the ink jet recording apparatus 1 (100) according to the embodiment,the ejection interval T1 after the base metal pigment ink compositiondescribed above is ejected from the first nozzle 26A (126A) and beforethe base metal pigment ink composition described above is ejected fromthe first nozzle 26A (126A) is within 100 μs. The adjustment of theejection interval is performed by the controller 70 described above. Inthe ink jet recording apparatus 1 (100) according to the embodiment,even if the ejection interval T1 is extremely short, the aforementionedbase metal pigment ink composition is used, so that the ejectionstability (waveform responsiveness) becomes excellent.

The ejection interval T1 is 100 μs or less, preferably in the range of20 μs to 100 μs, more preferably in the range of 30 μs to 90 μs, andparticularly preferably in the range of 40 μs to 80 μs. If the ejectioninterval T1 is 100 μs or less, the image can be recorded at a highspeed. Meanwhile, if the ejection interval T1 is 20 μs or greater, thedecrease of the ejection stability can be suppressed.

In addition, in the ink jet recording apparatus 1 (100), if the ejectioninterval after the color ink composition described above is ejected fromthe second nozzle 26B (126B) and before the color ink compositiondescribed above is ejected again from the second nozzle 26B (126B) isset to be T2, the ratio between the ejection intervals T1 and T2 (T1:T2)is preferably in the range of 0.7:1 to 1:0.7, and more preferably in therange of 0.8:0.9 to 0.9:0.8. In this manner, if the values of theejection intervals T1 and T2 are close to each other, the base metalpigment ink composition and the color ink composition can be stablyejected by using a common driving waveform and the landing positions ofthe both can be easily controlled so that there is an advantage in thata high definition image can be simply recorded.

The diameter of a nozzle hole is preferably 30 μm or less, morepreferably in the range of 15 μm to 30 μm, and particularly preferablyin the range of 20 μm to 25 μm. If the diameter of the nozzle hole is inthe range described above, the ejection stability of the ink becomessatisfactory.

As the ink jet recording apparatus according to the embodiment, theserial-type or line-type ink jet recording apparatus is used, but theink jet recording method is not particularly limited, as long as the inkcomposition can be ejected as ink droplets from fine nozzle holes andattached to a recording medium. Examples of the ink jet recording methodinclude a method of an electrostatic attraction type, a method ofejecting ink droplets by a pump pressure, a method of using thepiezoelectric element, and a method of heating and foaming ink dropletsby a microelectrode and ejecting ink droplets, and the like. Amongthese, a method of using a piezoelectric element can be preferably used.

In addition, the deformation shape of the piezoelectric element is notparticularly limited, and may be any one of a longitudinal modedeformation, a shear mode deformation, and a bending mode deformation.Among these, in view of the realization of the high definition and thereduction of the size of the head, the ink is preferably ejected byperforming the bending mode deformation. In addition, for the samereason, the thickness of the piezoelectric element is preferably 10 μmor less, more preferably 5 μm or less, and still more preferably 3 μm orless. The main component of the piezoelectric element is preferably oneor more kinds selected from the group consisting of lead zirconatetitanate, potassium sodium niobate, and bismuth ferrite oxide, and morepreferably lead zirconate titanate.

2.2. Recording Medium

The recording medium P is not particularly limited, but in the ink jetrecording method according to the embodiment, a low-ink-absorbablerecording medium is preferably used.

Here, the “low-ink-absorbable recording medium” may be a recordingmedium in which the amount of the water absorption when 30 msec'/² haspassed from the start of the contact in the Bristow method is 10 mL/m²or less, and at least a recording surface has the property. According tothis definition, the “low-ink-absorbable recording medium” according tothe invention also includes a non-ink-absorbable recording medium thatdoes not absorb water at all. The Bristow method is a most common methodof measuring a liquid absorption amount in a short time, and is adoptedby Japan Technical Association of the Pulp and Paper Industry (JAPANTAPPI). The details of the test method is described in Standard No. 51“Paper and Paperboard-Liquid Absorbency Test Method-Bristow Method” of“Japan TAPPI Paper and Pulp Test Methods 2000”.

Specific examples of the low-ink-absorbable recording medium includes asheet, a film, a textile product, and the like containing the lowabsorbable material. In addition, the low-ink-absorbable recordingmedium may be a recording medium including a layer containing a lowabsorbable material (hereinafter, referred to as “low absorbable layer”)on the surface of a base material (for example, paper, fiber, leather,plastic, glass, ceramics, and metal). The low absorbable material is notparticularly limited, and may include an olefin-based resin, anester-based resin, an urethane-based resin, an acryl-based resin, and avinyl chloride-based resin. In addition, overall characteristics such asa thickness, a shape, a color, a softening temperature, hardness, andthe like of the low-ink-absorbable recording medium are not particularlylimited.

3. EXAMPLES

Hereinafter, the invention is described in detail based on the examples,but the invention is not limited thereto. A “Part” and “%” in theexamples and the comparative examples are values based on mass, if notdescribed otherwise.

3.1. Manufacturing of Base Metal Pigment Ink Composition 3.1.1.Preparation of Pigment Dispersion Liquid for Base Metal Pigment Ink

The base metal pigment ink composition was prepared to manufacture thepigment dispersion liquid for base metal pigment ink. As a manufacturingmethod, a polyethylene telephthalate film having flat surfaces(arithmetical average surface roughness Ra was 0.02 μm or less) wasfirst prepared.

Subsequently, cellulose acetate butyrate (butylation ratio of 35% to39%) was applied to one entire surface of the film. Then, a filmconfigured with aluminum (hereinafter, referred to as “aluminum film”)was formed by using an evaporation method on the surface to which thecellulose acetate butyrate was applied.

Subsequently, a film on which an aluminum film was formed was put into asolvent presented in Table 1, and an ultrasonic wave was applied byusing a homogenizer. Accordingly, a dispersion liquid of flat aluminumparticles (particles to be mother particles) was obtained. The contentof the aluminum particles in the dispersion liquid was 3.7% by mass.

Subsequently, with respect to 100 parts by mass of the aluminumparticles, 20 parts by mass of 2-(perfluorohexyl)ethyl phosphonate wasadded to a dispersion liquid containing aluminum particles obtained asdescribed above, ultrasonic waves were applied for 3 hours at 55° C. ofthe liquid temperature, and the surface treatment of the aluminumparticles was performed. After the completion of the reaction, in acentrifuge (6000 rpm×30 minutes), centrifugal sedimentation wasperformed on aluminum particles subjected to the surface treatment, thesupernatant portion was removed, the solvent presented in Table 1 wasadded, the ultrasonic wave was further applied so that the aluminumparticles were dispersed again, and thus the dispersion liquid(re-dispersion liquid) in which the content of the aluminum particle was3.7% by mass was obtained. The re-dispersion liquid was concentrated byan evaporator, and thus paste dispersion liquid (dispersion medium:solvent presented in Table 1) in which the content of the aluminumparticle was 10% by mass was obtained. The average thickness of thealuminum particle obtained in this manner was 20 nm.

The obtained pigment dispersion liquids 1 to 6 for base metal pigmentink were used, the particle size distributions of the base metalpigments contained in the pigment dispersion liquids were measured by aparticle size distribution meter (Product name: Microtrac MT-3200EXmanufactured by Nikkiso Co. Ltd.), and the volume-based average particlediameters (D50, D90, and D10) were obtained.

The method of measuring the particle size distribution was as follows.First, 0.2 g of the dispersion liquid for base metal pigment ink (aftersurface treatment) obtained as described above was weighed, diethyleneglycol diethyl ether was added, and thus the dispersion liquid wasdiluted to 200 times (Measurement process 1). Subsequently, diethyleneglycol diethyl ether was circulated in the particle size distributionmeter, and the diluted solution obtained in Measurement process 1gradually added, until the detection sensitivity becomes the measurablerange (Measurement process 2). Subsequently, the measurement was startedin the condition presented in Table 2, and the particle sizedistribution was measured (Measurement process 3).

The average particle diameters of the base metal pigments obtained inthis manner are presented in Table 1.

In addition, the surface tension of the used solvent at 20° C. weremeasured by the automatic surface tensiometer CBVP-Z (manufactured byKyowa Interface Science Co., LTD.). The measurement results of thesurface tensions of the respective solvents are presented in Table 1.

TABLE 1 Pigment dispersion liquid for base metal pigment ink 1 2 3 4 5 6Base metal Kind of base Base metal Base metal Base metal Base metal Basemetal Base metal pigment metal pigment pigment 1 pigment 2 pigment 3pigment 4 pigment 5 pigment 6 Average 0.42 0.53 0.39 0.57 0.77 1.19particle diameter D50 (μm) Average 0.26 0.33 0.29 0.36 0.45 0.73particle diameter D10 (μm) Average 0.76 0.87 0.69 0.95 1.35 2.74particle diameter D90 (μm) Solvent Kind of solvent γ- N-methyl AcryloylDioxane Diethylene Diethylene butyrolactone pyrrolidone morpholineglycol diethyl glycol diethyl ether ether surface tension 43.9 41 44.637 23.3 23.3 (20° C.)

TABLE 2 Measurement condition of average particle diameter Refractiveindex N/A Shape N/A Density (g/cm³) — Solvent Diethylene glycol diethylether Refractive index 1.412 Measurement time (s) 30 Loading index —Reflected light power (mV) — DV 0.002488 TR 0.912939 Filter —Sensitivity — Nano-range adjustment — Monodisperse — Calculation modeMT3000 Distribution Volume

3.1.2. Preparation of Base Metal Pigment Ink Composition

In the compositions presented in Table 3, the respective base metalpigment ink compositions according to the examples and the comparativeexamples were prepared. Specifically, the organic compounds and thesurfactants were mixed and dissolved to obtain the ink solvents, thepigment dispersion liquids obtained as described above were added to theink solvent and were further mixed and stirred in a magnetic stirrer for30 minutes under normal temperature and pressure, and thus the basemetal pigment ink compositions were obtained. The obtained base metalpigment ink compositions were put into the ink pack, and thus the basemetal pigment ink compositions according to the examples and thecomparative examples were obtained.

TABLE 3 Exam- Exam- Exam- Exam- Exam- Exam- Comparative ComparativeReference ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 example 1 example 2example 1 Kind of ink composition Base Base Base Base Base Base Basemetal Base metal Black ink metal metal metal metal metal metal pigmentpigment pigment pigment pigment pigment pigment pigment ink 7 ink 7 ink1 ink 2 ink 3 ink 4 ink 5 ink 6 Base metal Base metal pigment 1 1.2 1.2pigment Base metal pigment 2 1.2 Base metal pigment 3 1.2 1.2 Base metalpigment 4 1.2 Base metal pigment 5 1.2 Base metal pigment 6 1.2 ColorantCarbon black 1.2 (Average particle diameter D50 = 100 nm) Solventγ-butyrolactone 25 50 (Organic N-methyl pyrrolidone 25 compound)Acryloyl morpholine 25 50 Dioxane 25 Diethylene glycol diethyl ether 2525 25 Triethylene glycol monobutyl ether 8 8 8 8 8 8 8 8 8 Celluloseacetate butyrate 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Diethylene glycolmethyl ethyl ether 65.2 65.2 65.2 65.2 40.2 40.2 65.2 65.2 65.2Surfactant BYK-UV3500 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Total (% bymass) 100 100 100 100 100 100 100 100 100 Evaluation Fixability A A B BA A C C — result Glossiness A B A B A B C C — Waveform responsiveness 1A A A A A A B C A Waveform responsiveness 2 A A A B A A C C A Waveformresponsiveness 3 A B A B A A C C A

Among the respective components described in Tables 3, the componentspresented by product names were as follows. •BYK-UV3500: Product name,silicone-based surfactant manufactured by BYK Japan K.K.

3.2. Evaluation Test 3.2.1. Fixability

A reformed machine of an ink jet printer SC-570650 (Seiko Epson Corp.)was used in the evaluation test. An ink cartridge was manufactured by acartridge exclusive for the product filled with the ink for evaluation.Subsequently, the obtained ink cartridge was mounted on a cyan array ofthe ink jet printer SC-570650, and commercially available ink cartridgeswere mounted on the other nozzle arrays. In addition, the mountedcommercially available ink cartridges except for the ink cartridgesmounted on the black array were used as dummies, and were not used inthe evaluation of the example. Therefore, the ink cartridges did notinfluence on the advantage of the invention. In addition, apiezoelectric element having a film thickness of 2 μm in the bendingmode deformation was used in the piezoelectric element of the ejectionhead of the printer. In addition, the main component of thepiezoelectric element was lead zirconate titanate.

Subsequently, on Photoshop CS3, data was manufactured by setting C to be80%, and the others to be 0%, the ink for evaluation mounted on the cyanarray was ejected to a vinyl chloride media JT5829R (Product name,manufactured by MACtac) by using the printer, and thus a recorded matteron which a solid pattern image in a 5 cm square was printed wasobtained.

Thereafter, when a printed surface of a printed matter left for 5 hoursin a laboratory under the condition of room temperature (25° C.) wasrubbed five times with cotton cloth under load of 500 g by using ColorFastness Rubbing Tester AB-301 (Product name: Tester Sangyo Co,. Ltd.),peeling state of the printed surface and the ink stain state on thecotton cloth was checked so that abrasion resistance (fixability) wasevaluated. The evaluation criteria of the abrasion resistance were asfollows.

-   A: Even if rubbing was performed five times, ink peeling or ink    stain on cotton cloth were not recognized-   B: After rubbing was performed five times, ink peeling or ink stain    on cotton cloth were slightly recognized-   C: After rubbing was performed five times, ink peeling or ink stain    on cotton cloth were recognized

3.2.2. Glossiness

The recorded matter was prepared on the same condition as the fixabilitytest described above, glossiness of the obtained recorded matter at aflap angle of 60° was measured by using a gloss meter (Product name:“MULTI Gloss 268” manufactured by Konica Minolta, Inc.). The evaluationcriteria of the glossiness of the obtained recorded matter were asfollows.

-   A: Glossiness was 550 or greater-   B: Glossiness was in the range of 450 to less than 550-   C: Glossiness was in the range of 350 to less than 450

3.2.3. Waveform Responsiveness

The printer was prepared on the same condition as the fixability testdescribed above, driving frequency was adjusted, and thus a recordedmatter on which a solid pattern image in a 50 cm square was printed wasobtained at an ejection interval of 125 microseconds (WaveformResponsiveness 1) which was about twice the normal driving frequency.The obtained image was evaluated by the criteria as follows. Inaddition, the ejection interval was changed to 83 microseconds and 42microseconds and Waveform Responsiveness 2 and 3 was evaluated.

Further, in the waveform responsiveness test, the same test wasperformed by using black ink composition presented in Test 3 in order tocompare the waveform responsiveness with general color ink.

-   A: can be used without problem in ink jet-type recording apparatus-   B: was difficult to be used in ink jet-type recording apparatus-   C: cannot be used in ink jet-type recording apparatus

3.2.4. Evaluation Result

The results of the evaluation test were presented in Table 3.

TABLE 3 Exam- Exam- Exam- Exam- Exam- Exam- Comparative ComparativeReference ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 example 1 example 2example 1 Kind of ink composition Base Base Base Base Base Base Basemetal Base metal Black ink metal metal metal metal metal metal pigmentpigment pigment pigment pigment pigment pigment pigment ink 7 ink 7 ink1 ink 2 ink 3 ink 4 ink 5 ink 6 Base metal Base metal pigment 1 1.2 1.2pigment Base metal pigment 2 1.2 Base metal pigment 3 1.2 1.2 Base metalpigment 4 1.2 Base metal pigment 5 1.2 Base metal pigment 6 1.2 ColorantCarbon black 1.2 (Average particle diameter D50 = 100 nm) Solventγ-butyrolactone 25 50 (Organic N-methyl pyrrolidone 25 compound)Acryloyl morpholine 25 50 Dioxane 25 Diethylene glycol diethyl ether 2525 25 Triethylene glycol monobutyl ether 8 8 8 8 8 8 8 8 8 Celluloseacetate butyrate 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Diethylene glycolmethyl ethyl ether 65.2 65.2 65.2 65.2 40.2 40.2 65.2 65.2 65.2Surfactant BYK-UV3500 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Total (% bymass) 100 100 100 100 100 100 100 100 100 Evaluation Fixability A A B BA A C C — result Glossiness A B A B A B C C — Waveform responsiveness 1A A A A A A B C A Waveform responsiveness 2 A A A B A A C C A Waveformresponsiveness 3 A B A B A A C C A

As presented in Table 3, if ink containing the organic compound havingthe specific surface tension (solvent) and the base metal pigment in thespecific range of the average particle diameter (D50) was used, it wasfound that the waveform responsiveness was satisfactory (Examples 1 to6).

Meanwhile, if the ink that contains the base metal pigment in thespecific range of the average particle diameter (D50) but does notcontain the organic compound having the specific surface tension(solvent) was used, it was found that the waveform responsiveness, theglossiness, and the fixability were decreased.

The invention is not limited to the embodiment as described above, butvarious modifications are possible. For example, the invention includesconfiguration which is substantially the same as that described in theembodiment (for example, configuration that has the same function,method, and result, or configuration that has the same purpose andadvantage). In addition, the invention includes configuration in which aunessential portion in the configuration described in the embodiment isreplaced. Also, the invention includes a configuration that achieves thesame effect as the configuration described in the embodiment or aconfiguration that can achieve the same purpose. In addition, theinvention includes the configuration described in the embodiment towhich the well-known technique is added.

The entire disclosure of Japanese Patent Application No.:2014-094416,filed May 1, 2014 is expressly incorporated by reference herein.

What is claimed is:
 1. An ink jet recording apparatus, comprising: abase metal pigment ink composition; and a first nozzle that ejects thebase metal pigment ink composition, wherein the base metal pigment inkcomposition contains a flat base metal pigment of which a 50% averageparticle diameter D50 is in a range of 100 nm to 1 μm, and an organiccompound of which a surface tension at 20° C. is 35 mN/m or greater, andwherein an ejection interval T1 after the base metal pigment inkcomposition is ejected from the first nozzle and before the base metalpigment ink composition is ejected again from the first nozzle is within100 μs.
 2. The ink jet recording apparatus according to claim 1, whereina difference between a 90% average particle diameter D90 of the basemetal pigment and a 10% average particle diameter D10 of the base metalpigment (D90−D10) is in a range of 0.1 μm to 0.8 μm.
 3. The ink jetrecording apparatus according to claim 1, wherein a 90% average particlediameter D90 of the base metal pigment is in a range of 0.3 μm to 1.2μm.
 4. The ink jet recording apparatus according to claim 1, furthercomprising: a color ink composition containing a colorant; and a secondnozzle that ejects the color ink composition, wherein the colorant is adye, or a pigment in which a 50% average particle diameter D50 is 400 nmor less, and wherein when an ejection interval after the color inkcomposition is ejected from the second nozzle and before the color inkcomposition is ejected again from the second nozzle is referred to asT2, a ratio between T1 and T2 (T1:T2) is in a range of 0.7:1 to 1:0.7.5. The ink jet recording apparatus according to claim 1, wherein adiameter of the first nozzle is 30 μm or less.
 6. The ink jet recordingapparatus according to claim 1, wherein the ink jet recording apparatusis a line-type ink jet recording apparatus that causes one of arecording head or a recording medium to be fixed and scans the other soas to record an image on the recording medium, and wherein the firstnozzle, and a second nozzle that ejects a color ink compositioncontaining a colorant which is a dye, or a pigment having a 50% averageparticle diameter D50 of 400 nm or less are installed on differentrecording heads, and arranged in a direction of the scanning.
 7. The inkjet recording apparatus according to claim 1, wherein the first nozzle,and a second nozzle that1 ejects a color ink composition containing acolorant which is a dye, or a pigment having a 50% average particlediameter D50 of 400 nm or less are installed on the same recording head,wherein the recording head includes a first nozzle array and a secondnozzle array and performs scanning in a main scanning direction, whereinthe first nozzle array contains the first nozzle, and a plurality ofnozzles that eject the base metal pigment ink composition are arrangedin a sub scanning direction intersecting the main scanning direction,wherein the second nozzle array contains the second nozzle, and aplurality of nozzles that eject the color ink composition are arrangedin the sub scanning direction, and wherein the first nozzle array andthe second nozzle array are used in a divided manner for every groupsincluding a predetermined number of nozzles in the sub scanningdirection.
 8. The ink jet recording apparatus according to claim 1,wherein the organic compound is at least one of a heterocyclic compoundand an active energy ray polymerizable compound.
 9. The ink jetrecording apparatus according to claim 1, wherein the content of theorganic compound is 5% by mass or greater with respect to a total massof the base metal pigment ink composition.
 10. The ink jet recordingapparatus according to claim 1, further comprising: a piezoelectricelement that ejects the base metal pigment ink composition from thefirst nozzle; and a recording head that includes the first nozzle andthe piezoelectric element, wherein the piezoelectric element performs abending mode deformation and ejects the base metal pigment inkcomposition from the first nozzle.